- Nutrition -

Shaking Out the Truth About Salt


We’re all being told to reduce our sodium intake. But some experts argue that we aren’t getting the whole story — about why salt may not be the killer we’ve been told, and where the real dangers may lie.

In case you haven’t heard, a national debate is playing out regarding America’s favorite flavoring: salt.

The arguments of the anti-salt contingent are nothing new: For more than 40 years, experts have been warning us of salt’s health risks, emphasizing its links to high blood pressure and heart disease. They insist that we’d all be better off if we ate less of the stuff. A lot less.

Somewhat more surprising have been the arguments erupting from the other side. They say salt isn’t nearly as dangerous as it’s being made out to be — at least not for many of us. And they posit that a heavyhanded push to reduce sodium for the entire population could have unintended, unfortunate consequences.

It all started last January when the United States Department of Agriculture (USDA) took aim at salt in the 2010 Dietary Guidelines. To draw the public’s attention to the hazards of salt, the USDA highlighted a study published in 2010 in the New England Journal of Medicine. It postulated that up to 92,000 deaths a year could be averted if Americans radically reduced their daily salt intake (on average, currently the equivalent of 1.5 teaspoons) by a half-teaspoon per day.

The USDA nabbed headlines with its salt-slashing recommendations, but it also elicited vocal objections from a number of well-respected experts. Some of them recalled similar high-profile crusades against saturated fat and cholesterol — which were subsequently shown to be based on faulty scientific hypotheses, and which arguably wound up backfiring in unexpected ways.

These experts point out that the case against sodium is far from iron-clad. A meta-analysis published last August in the American Journal of Hypertension found no evidence that cutting sodium intake in people with normal or high blood pressure reduces the risk of heart attacks or strokes. And the authors of a study published last May in the Journal of the American Medical Association concluded that eating less salt was associated with an increase in deaths from heart disease.

In short, those opposed to blanket cuts in sodium are concerned that the USDA is being overly aggressive, given the current state of the science.

“I think guidelines that affect millions of people should be made on the basis of unambiguous scientific evidence,” says Niels Graudal, MD, a Danish researcher who has published many research studies on sodium.

“For instance, many studies show that smoking tobacco leads to cancer, chronic lung disease, atherosclerosis and increased mortality,” says Graudal, “but no studies show that tobacco is healthy. Therefore, it is easy to make guidelines about smoking. However, the evidence concerning sodium reduction is diverse, and has been for more than a hundred years. Every time a new study appears that shows that sodium reduction is beneficial, another one is published that shows the opposite.”

One of the challenges here is that individual requirements for sodium, and responses to it, vary greatly. So asking an entire population to reduce a necessary nutrient wholesale, and cranking the food production machinery into a salt-reduction frenzy, poses some dangers that cannot be easily assessed, notes Graudal. And this is what leaves him and many other experts worried: “I think the current sodium-reduction guidelines could wind up inadvertently killing more people than they save.”

Blood Pressure Boondoggle

Meanwhile, in conventional medical circles, the war against salt continues. In America each year, nearly 400,000 deaths are attributed to high blood pressure, according to the Centers for Disease Control and Prevention. If reduced sodium intake helped to lower blood pressure among a large population, the positive public health implications would be tremendous, says Ralph Sacco, MD, past president of the American Heart Association (AHA) and chairman of neurology at the University of Miami. But the hitch — and it’s a big one, in some experts’ minds — is that “if.”

First, not everyone’s blood pressure responds to salt. How the body handles sodium is scripted by a complex interplay of genes and diet. Some people appear to be “salt sensitive,” meaning their blood pressure swells and dips in response to how much salt they eat. But nobody knows for sure what percentage of people fall into that category because there is no simple way to test your body’s sensitivity to salt. Estimates vary widely. Judging from the USDA guidelines, it’s at least half the U.S. population. (They state that “African Americans; individuals with hypertension [high blood pressure], diabetes, or chronic kidney disease; and individuals ages 51 and older . . . [are] even more responsive to the blood pressure-raising effects of sodium than others.”

Graudal, however,  along with many other experts, believes the salt sensitive population comprises only “a small minority of people with genetically determined hormonal variations.”

If you do have high blood pressure, there is no reason to assume that salt is causing the hypertension, says Paul Rosch, MD, FACP, clinical professor of medicine and psychiatry at New York Medical College and president of The American Institute of Stress. “The vast number of people you see with hypertension have no specific, obvious cause for it,” he says. “Hypertension, like fever, is not a diagnosis but rather a description. It is simply an elevated blood pressure reading . . . that can have many different causes. That helps to explain why we have around 100 drugs to treat high blood pressure.”

Even if you do fall into one of the categories of people the USDA deems more susceptible to the “blood pressure-raising effects of sodium,” says Rosch, you could first try more substantive lifestyle approaches to reducing your blood pressure, including reducing stress, exercising, quitting smoking and embracing a vegetable-rich diet.

Hypertension researcher Hillel Cohen, DrPH, MPH, an epidemiologist at the Albert Einstein College of Medicine in the Bronx, agrees that individuals — even those in so-called at-risk categories — should consult with clinicians to discuss a variety of nonpharmacological methods of reducing blood pressure: “No matter what group you are in, what’s true for the average is not necessarily true for the individual. Broad assumptions about categories of people may not apply.”

“That’s the challenge when you try to develop public policy out of epidemiology,” says Roger Clemens, president-elect of the Institute of Food Technologists and a member of the USDA 2010 Dietary Guidelines advisory committee. “Sodium reduction is a step. It doesn’t mean everyone will respond the same way. But you do the best you can, and we’ve got to do something.”

Why We Need Salt

The problem, say salt proponents, is that the “something” conventional docs want to do is likely to have some significant negative consequences they aren’t currently factoring into their life-saving projections.

All of the experts can agree that getting a certain amount of salt in your diet is a biological imperative. Sodium, which along with chloride makes up a salt molecule, is a key player in dozens of different biological processes, from muscle contractions (e.g., the heart pumping) to nerve impulses (e.g., the brain firing) to balancing the movement of water in and out of cells. It also interacts closely with a variety of other chemicals and minerals in the body.

Precisely how much salt is enough, and how much is too much — particularly in a specific individual — is not entirely clear. It depends on other dietary factors (like potassium and water intake), as well as activity levels and genetic predispositions.

Early humans got most of their salt from meat. A 3-ounce serving of red meat, for example, has roughly 52 mg of sodium. Today, Americans eat an average of 3,400 mg of sodium daily — about 55 percent more than our parents ate, and several times more than our ancestors consumed.

While most experts agree that modern Americans get plenty of salt in their diets, it’s not clear just how much of a reduction any one individual can tolerate before negative health impacts ensue. Critics like Graudal assert that not only will everyone’s blood pressure not respond to sodium reduction, but overzealous reductions in salt could directly upset the biochemistry of some.

Many studies show that sodium reduction, even within the limits of the current guidelines, can lead to increased cholesterol and triglycerides in the bloodstream, according to Graudal. Also, he adds, “the endocrine system that conserves salt in the body (the renin-angiotensin-aldosterone system) is activated proportionally to the degree of sodium reduction — and increased renin is a prognostic marker for increased mortality.”

Translation? Drastically reducing salt could throw some people’s  hormonal health off kilter.

Cohen agrees and adds that “there is also some evidence that lower sodium is associated with greater insulin resistance.” As with the studies about too much salt, though, he cautions, “the evidence is incomplete and there is likely very large variation among individuals.”

The Food-Processing Machine

Today, the vast majority of the salt in the average American’s diet (75 to 80 percent) is coming not from hand-wielded kitchen saltshakers but from industrially processed food products. For example, an unadulterated 4-ounce serving of chicken contains 60 mg of sodium. But much of the chicken sold in supermarkets today is “enhanced,” meaning it’s injected with salt water. As a result, that same 4-ounce serving now has up to 400 mg of sodium — before you’ve seasoned it in any way.

“Our bodies are not designed to handle the tsunami of salt delivered day in and day out by processed foods,” says Kathie Swift, MS, RD, LDN, coauthor The Inside Tract: Your Good Guide to Great Digestive Health (Rodale, 2011). “Because  we don’t eat enough high-potassium vegetables and fruits to balance it out, our sodium-to-potassium ratio is totally lopsided.” Even so, she says, “In many products,” the profusion of “refined grains, sugars and trans fats remains a much bigger nutritional concern” than salt.

In response to the recent USDA guidelines, though, food companies are scrambling to reduce salt in products of all kinds. Recent additions to store shelves include everything from low-sodium microwaveable pancakes to low-sodium chicken tenders — a reminder that simply reducing the sodium in a given product does not necessarily render it healthy or even nutritionally superior.

Meanwhile, for manufacturers, the singular goal of reducing sodium remains a formidable challenge, says Clemens: “Sodium chloride is the cheapest, most functional molecule in the food supply after water,” he notes. “If it were easy to substitute salt in the food supply, it would have been done 30 years ago.”

Salt is used as a preservative in processed foods, and as a texturizer, and as a chemical catalyst. Forced reductions in salt will encourage food manufacturers to seek creative substitutions, some of which (from molecular-level tinkering to fungus-derived flavorings) may not turn out to be entirely healthy.

Such unintended consequences are not necessarily small issues, notes Cohen, recalling unforeseen problems that evolved from three decades’ worth of low-fat diet obsession: “That may have contributed to increased refined carbohydrate intake,” he says, “which may in turn have contributed to the rise of obesity and insulin resistance.”

So far, adds Cohen, no proposal to restrict sodium has included a mechanism to monitor the results of associated changes in processing, formulation or consumption.

So what’s a consumer to do? When shopping, remember that food manufacturers are being incentivized to come up with all sorts of sodium substitutes. Stick with products that have simpler, more natural, whole-food ingredient lists. Better yet, cut back on processed foods and stick with whole foods as much as possible — especially potassium-rich fruits and vegetables, which help to naturally balance sodium intake. When cooking, rather than avoiding salt altogether, strive to season your food just before eating, and use high-quality salts (see “Make a Salt Swap,” sidebar). And, instead of obsessing about salt, try ditching things like sugar, trans fats and processed flours, all of which will likely have a larger impact on your overall health.

Above all, don’t panic. “If you eat a healthy and varied diet, you probably do not have to worry much about your sodium intake,” says Graudal.